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Flex Sensor Glove
Goal The goal of this project is to create a wearable glove integrated with flex sensors so that as the wearer bends his/her fingers it translates to a quantative value in our computer. Basically, the goal is that when you bend your fingers we can control things. Ideas This is a wide open project that could be applied to many different uses. Here are a few ideas *Control robotic hand *Stenograph typing *Creating sounds by certain finger positions Hardware The project consists of only a few items. *A glove *Flex sensors *Needle and thread *Voltage Divider (resistor or potentiometer ) *Arduino Uno *Arduino Wireless shield *Wire We will create the flex sensors ourself. Once they are built and working, we will stitch them into the fingers of a glove. Our resistors for the voltage divider will be soldered into a PCB and attatched to the glove. The arduino Uno will also be attatched to the glove. We are not sure how we will do this yet, but will decide once we have the sensors stitched into the glove. At first, it will be attatched to a computer by wires, but after we get it working that way, we will use a Wireless Shield to send the ouptut to a computer. Electronics Flex Sensors As opposed to spending $15 per finger on the flex sensors, we opted to build our own flex sensors following website http://www.instructables.com/id/Stickytape-Sensors/ Creating our own flex sensors proved to be quite interesting and so far are working relatively well for our purposes. The construction involves only 3 items. *Electrical Tape *Conductive Thread *Velostat Those three components are sandwiched together as electrical tape--conductive thread--2 layers of velostat--conductive thread--electrical tape. It is important that each strand of conductive thread pokes out of only one side of the sandwich and that the two conductive wires do not directly touch. It is also important that all of the Velostat is contained within the electrical tape to prevent any sort of interferance by touching something else. Many online tutorials suggest using the bags that Integrated Circuits are typically packaged in instead of Velostat. However, it is only true of bags that are conductive (typically those that are very dark). We opted for purchasing pure, brand name Velostat so that we would not worry about complications arising from using unofficial components. We chose to go with only 2 strips of Velostat in the sandwich, because it seemed to work well. Adding more Velostat will make the flex sensor more resistive, meaning that it will have to be bent more to output the same value as one with less layers. Voltage Divider A potentiometer is a variable resistor. We are currently using a potentiometer in our circuit, but we may switch to using a resistors because they are smaller. The potentomenter is put in series with a single flex sensor. The purpose of this is because, as the flex sensor bends, it's resistivity changes, but the overall voltage of the output going to the Arduino analog input does not change. The idea is that you put two resistors in series between power and ground: one that changes resistance (your sensor), and one of a known, fixed resistance. At the point in between the two resistors, you can measure how much the voltage has dropped through the first resistor. This value changes as the ratio of resistances between variable and fixed resistors change.http://protolab.pbworks.com/w/page/19403657/TutorialSensors A potentiometer is in essence a voltage divider because it directly affects the voltage output of a circuit. A single resistor does not affect the output voltage (th e output going to the analog input of the Arduino), it only affects the current. A voltage divider of two resistors does affect the output voltage between the series of two resistors. The analog input of the arduino reads the voltage between 0-5 (represented by the values 0-1023) so we need a circuit where the change in resistance of the flex sensor changes the output voltage.